1. The bolts that welded on the valve discs should not be too long, otherwise they will press against the flow port of the valve. Thus the sealing surface will be raised and the valves can not have good sealing performance.
2. When valves are under assembly, the inspection should be done on the opening of the adjusting screw to ensure the sealing surface match tightly.
3. Select the appropriate adjust pad. Generally the thickness of the pad should be slightly below or equal to the bench height of the disc sealing surface .To make the soft seal fits closely with the valve disc sealing surface and in the same level. What’s more, to prevent the drop off of the compression nuts, the locking nut should be loosen properly after fully tighten up.
4. Consider about the working condition of the flow fluid, choose the suitable soft gasket for the medium is important. Appropriate measures should be taken to avoid the corrosion by medium or deformation because of the high temperature ,which are the main factors that will affect the usage of valves.
Above are the main protective measures for bi-directional butterfly valves.